The F-35B is now in flight testing at the Patuxent River naval air station in Maryland. The radical hover-jet also achieved another first yesterday, making its first short-roll takeoff assisted by its vertical-thrust equipment:

The F-35B has a vertical-thrust fan, driven by a shaft from the engine, mounted in a shaft behind the cockpit. The big fliptop lid seen in the videos covers the top of the shaft in normal flight, while the smaller dorsal doors just behind it allow extra air into the engine for high-power hovering operations. Simultaneously, the jet's exhaust swivels downward in hover mode. There are also two small outlets for engine gas under the wings, to stop the jet rolling over.

The F-35B is intended for service with the US Marine Corps, Royal Navy and RAF, replacing existing fleets of Harrier jumpjets. There is also a normal runway-only version of the jet (F-35A) which will go to the US air force and many international customers, and a version designed for carrier catapult launch and arrested landing (F-35C) for the US Navy.